1. Technical Field
The present invention relates to headrest operating devices that are operable to move a headrest toward a head portion of a person seated on a vehicle seat of a vehicle when a backside collision occurs. In this specification, the term “back side collision” is used to mean the situation where an object, such as another vehicle, collides with the backside of the vehicle.
2. Description of the Related Art
A vehicle seat is known that has a mechanism for supporting a head portion of a seated person by moving a headrest toward the head portion of the seated person when a backside collision occurs. For example, Japanese Laid-Open Patent Publication No. 2005-95237 teaches a headrest operating device for moving a headrest based on a load that may be applied to a seat back by a seated person when a backside collision occurs.
According to the headrest operating device of the above publication, a pressure receiving mechanism disposed within the seat back for receiving the load from the seated person is configured not to operate unless the backside collision occurs. Therefore, the headrest may not be accidentally moved even if the seated person leans on the seat back to apply a large load to the seat back. More specifically, the pressure receiving mechanism is coupled to a weight that can move by an inertia force when the backside collision occurs. The weight is coupled to a lock mechanism for locking and unlocking the headrest, so that the lock mechanism maintains the lock condition of the headrest unless the inertia force moves the weight.
However, the headrest operating device of the above publication requires a relatively large installation space for the pressure receiving mechanism, the lock mechanism and a device for detecting the backside collision.
Thus, there is a need in the art for a headrest operating device that has an accidental operation preventing device and has a compact construction.